Sensing and control apparatus for webs

ABSTRACT

A sensing and control apparatus for detecting thickness irregularities or the like in webs, such as paper webs. The apparatus includes a reference roller rotatably mounted about a fixed horizontal axis, and a motion detector roller mounted for vertical shifting movement, the rollers being adapted to lie tangent to a web disposed therebetween. A cross-shaft is provided, the shaft being mounted for rotation about a horizontal axis parallel with the axis of rotation of the rollers. Follower means on the cross-shaft engage on seats provided on the detector roller, such that upward movement of either end of the roller caused by a flaw in the web will induce a rotation of the shaft. The connection between the follower and roller is such as to permit pivotal movement about an axis essentially perpendicular to the pivot axis of the cross-shaft. Motion magnifying means for operating a cutoff switch are connected to the cross-shaft.

United States Patent Hogget a1 200/61.13X

3,364,527 1/1968 Ramo 19/65CRX 3,502,827 3/1970 Beebe PrimaryExaminerRobert K. Schaefer Assistant Examiner-M. GinsburgAttorney-Arthur B. Colvin ABSTRACT: A sensing and control apparatus fordetecting thickness irregularities or the like in webs, such as paperwebs. The apparatus includes a reference roller rotatably mounted abouta fixed horizontal axis, and a motion detector roller mounted forvertical shifting movement, the rollers being adapted to lie tangent toa web disposed therebetween. A cross-shaft is provided, the shaft beingmounted for rotation about a horizontal axis parallel with the axis ofrotation of the rollers. Follower means on the cross-shaft engage onseats provided on the detector roller, such that upward movement ofeither end of the roller caused by a flaw in the web will induce arotation of the shaft. The connection between the follower and roller issuch as to permit pivotal movement about an axis essentiallyperpendicular to the pivot axis of the cross-shaft. Motion magnifyingmeans for operating a cutoff switch are connected to the cross-shaft.

PATENIEUUEBMIQYI D 3527944 sum l-UF 4 I. I nhi- INVI'IN'I'UR. DONALD G.FIELD ATTORNEY PATENTEnnEcmmn 3521944 sum 3 0F 4 INVHN'I'UIL DONALD G.FIELD SENSING AND CONTROL APPARATUS FOR WEBS This invention is in thefield of apparatus for detecting thickness variations in webs or thelike. Such thickness variations may be the result of detritus, sliversor like elements which are not integrated into the web or may be theresult of the uneven formation of the web itself.

There is a growing market for prepackaged towels, dressings and likearticles which comprise severed lengths of web material which have beenfolded or otherwise processed and sealed or encapsulated within foil orlike envelopes. Such envelopes may or may not incorporate a liquidreagent which saturates the towel or dressing, in accordance with itsintended end use.

It is highly desirable that the web material, which is to besubsequently folded and packaged, be controlled as to its thickness andbe free from detritus, slivers or other extraneous matter. Theimportance of the requirement that the packaged process be free fromdetritus will be readily appreciated when it is realized that thefinished products may be used as eye swabs, dressings, bandages, vaginalwipes and the like.

Since the web material used in the formation of such products istypically folded along a multiplicity or lengthwisely extending foldlines, it will be readily appreciated that a thickness area within theweb itself which may happen to coincide with a fold line will, at best,result in.the production of an article having an exaggerated thickness,due to the fact that subsequent folding steps magnify the thickness ofthe web in areas in registry with the defective area. Since suchproducts are typically fed through a fan folding apparatus for theformation of the longitudinal folds, if the high bulk defective area ofthe web should coincide with a fold area, it is conceivable that thematerial may jamwithin the fan folding apparatus, requiring asignificant interruption in production to permit the jam to be cleared.I

Attempts have heretofore been made toprovide high-speed sensingapparatuses which may automatically interrupt production when detritusor an overthick portion of,a web is sensed. Such apparatuses haveincorporated electric eye sensors, black spot sensors, as well as avariety of mechanical sensors. However, in practiceno mechanicaldetector heretofore known has been capable of .the simultaneousadvantages of high accuracy, ready adjustment in accordance with thedesired dimensional range, speed, and ability to sense a defect at anyposition along the entire width of the web. This last mentionedrequirement has been particularly troublesome in 1 that, wheremechanical detectors heretofore known have been able to sense athickness variation at one widthwise position along a web, no such knownapparatus has been equally sensitive across the entire width of the web.

The present invention relates to an automatic thickness detectorresponsive to a predetermined range of thickness variables, whether byway of integral defects in the web or detritus deposited on the web. Theapparatus will sense a thickness variation without regard to itsposition transversely of the web.

The apparatus includes a pair of rollers or like means, one

I of which is preferably fixed for rotation about a reference axis.

selected magnitude, will trip the switch to effect a desired result,such as interruption of the web feed, etc.

It is accordingly an object of the invention to .provide a web thicknessdetector or the like which is simple in construction, and which may bereadily modified to process webs of a variety of thicknesses.

A further object of the invention is to provide a detector of the typedescribed which may be readily adjusted to control the permitted rangeof thicknesses and the extent of defects which will be tolerated.

A further object of the invention is the provision'of a device of thetype described which will permit detection of a defe'ctat any positionalong the width of the continuously advancing web.

Still a further object of the invention is the provision of a device ofthe type described which is simple in construction durable, andpreferably employs means to yieldingly urge the rollers toward eachother.

To attain these objects and such further objects as may appear herein orbe hereinafter pointed out, reference is made to the accompanyingdrawings, forming a part hereof, in'which:

FIG. I is a side elevational view of a web detector apparatus of thetype described;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a magnified plan view of the section between the arrows 3-3 ofFIG. 1;

FIG. 4 is a discontinuous vertical section taken on the staggered line44 of FIG. 3,

FIG. 5 is a magnified vertical section taken on the line 5-5 of FIG. 3;

FIG. 6 is a magnified detail view of the control mechanism and the limitswitch, and

FIG. 7 is a detail view taken along line 7-7 of FIG. I.

Referring now to the drawings, there is shown in FIG. I a web detectorapparatus incorporated as an initial station in a mechanism for formingpackets. In such packet forming apparatus, the web W is led from asupply roll S, through the detector assembly 10, and then to fan foldingapparatus 11 which forms no part of the present invention.

The fan folder, as best seen in FIG. 2, takes the full width web andforms a multiplicity of longitudinally extending folds thereon, to forma multiple-ply folded web suitable for packaging in a small envelope.

The web supply roll S incorporates a support shaft 12 seated withinspaced-apart, upwardly open bearing seats 13, permitting the supply rollto be mounted by lowering it into position. The web material may bepayed off from the supply roll S by a pulling force, it beingappreciated that by reason of the considerable weight of the supplyroll, a fairly substantial tension is induced in the web in the courseof such pulling.

It will be further appreciated that, despite considerable manufacturingcare, the web in the bulk supply S may incorporate detritus by way ofslivers, splinters or the like which may be either loosely appended tothe surface of the web or adhered to or embodied in the web. As aninitial means for reducing the amount of loosely carried detritus, theframe 14 of the detector apparatus is provided with a scraper assembly15.

The scraper assembly includes an elongated substantially rectangular arm16, the lower end 17 of which is mounted to a trunnion l8, suitablypivotally carried by spaced bearings formed on the frame. A spring 19 istensioned between the spring seat 20 on vertical strut 2 1 of the frameand an adjustable seat 22 movably mounted on the arm 16, the spring 19serving to impart an anticlockwise rotation to the arm 16 when the sameis viewed as shown in FIG. 1.

At the upper end 23 of the arm 16, there is carried a scraper bladeassembly 24 comprising a block 240 pivoted as at 24b and which carries ascraper blade 246, which is yieldingly urged against the periphery ofthe web W as it is unrolled from the bulk supply 8.

Furthermore, the upper end of arm 16 carries a pair of tapered rollers16a which ride against the sides of the supply roll S to center thelatter.

It will be appreciated that the scraper blade 24c will remove looselyentrained detritus from the surface of the web which is scanned by theblade, the spring 19 serving to maintain the scraper head in engagementwith the web despite the progressively diminishing size of the bulksupply roll S.

In addition to scraper assembly 15, there is a second scraper assembly15' which reacts against the opposite side of the web. This assembly maycomprise a blade 15a secured by screws 15b in elongated adjustment slots15c so that the edge or the blade may lightly contact the web surface.

The web W passes from the bulk supply roll S between a pair of rollersand 26, the lower roller 25 being referred to hereinafter as a referenceroller, and the upper roller 26 being referred to as a detector roller.The rollers 25, 26 are rotatably mounted on the frame for rotation abouthorizontal, vertically spaced-apart axes.

Reference roller 25 comprises the roller over which the web W is pulledfrom the supply roll S, the detector roller 26 functioning as a detectorin the manner hereinafter set forth.

Reference roller 25 is driven solely through the force exerted on theweb and illustratively has no independent drive means.

Reference roller 25 is journaled in such manner as to have its uppermostsurface or peripheral portion constantly disposed in a preselectedhorizontal reference plane. In contrast, the detector roller 26, as bestseen in FIG. 5, is mounted in such manner as to permit vertical shiftingmovement thereof. To this end, detector frame 28 is provided with a pairof spaced, parallel side guides 29, 29, within which are formedvertically directed guideway channels 30. Guide blocks 31, 31 includeslide portions 32 extending into the channels to permit the desiredindependent vertical movement of each end of the shaft while preventingrotary tilting of the blocks with respect to the channels.

The blocks 31 include bearing portions 33 which rotatably carry thedistal ends 34, 34 of the detector roller 26.

A wiper blade member 35, illustratively a nylon strip, is provided,which performs the function of clearing any lint, detritus or the likefrom the surface of the detector roller 26. The blade 35 includes aclamped'end 36 which is bolted to the frame between upper and lowerspacer blocks 37, 38, which blocks are held to the frame by clamp bolts39.

The blade 35 includes a free end 40 which curls over, wipingly engages,and downwardly, yieldingly presses against the upper surface of detectorroller 26. Preferably the width of the blade 35 is greater than thewidth of any web which will be fed in the apparatus so that it mayperform its lint gathering functions across the entire widthwise extentof the web.

Means are provided for varying the cleaning force exerted by the freeend 40 of wiper blade 35. For this purpose, a pair of stanchions 41, 41are fixed to the frame adjacent the lateral portions 42, 43 of the blade35. Each of the stanchions carries a collar 44, which collar portionsmay be heightwisely adjusted in relation to the stanchions 41. Each ofthe collars 44, 44 is connected to the opposite end of adjustment bar 45which extends transversely beneath an undersurface portion of the blade35.

It will be appreciated that the lower limit of movement of the blade 35will be defined by the heightwisely adjusted position of the bar 45which forms a lower stop portion for the blade. The bar 45 is adjustedby setting the position of the collars 44, in such manner that the freeend 40 of the blade will press downwardly against the roller 26 with adesired force.

It is further important that the apparatus be responsive to a lifting ofany portion of the upper roller, whereby the apparatus is sensitive tothickness variations appearing at any transverse position across thewidth of the web W.

The sensing apparatus includes a shaft 46 extending through andpivotally mounted within coaxially aligned bearings 47, 47 formed in theside frame portions 29. A pair of cap members 48, 48 is fixed to thedistal ends of the shaft 46 which project beyond the sides 29, the capscarrying rearwardly directed extensions 49, 49 disposed in asubstantially horizontal plane. The extensions 49 carry longitudinallyadjustable weights 50, 50 which, when viewed in the orientation of FIG.1, would ordinarily tend to impart an anticlockwise rotation to theshaft 46. Such anticlockwise rotation of the shaft is resisted by forcetransmission or follower members extending between the shaft 46 and seator saddle supports 51, 51 formed at the upper ends of the slide blocks31, 31.

As best shown in FIGS. 3 and 4, a follower 52, made fast to the shaft 46and extending at right angles therefrom, is seated in the saddle 51 ofthe left-handmost block 31 having slide portion 32. A second follower 54made fast to shaft 46 and extending at right angles therefrom is seatedon the saddle 51 of the right-handmost block 31. The follower 54 has arearwardly extension which defines a motion magnifying arm 53.

The follower 52 is keyed to the shaft 46 against relative movement, asby locking bolt 55. In similar fashion, locking bolt 56 keys thefollower 54 and its associated motion magnifying arm 53 to the shaft 46.

The end 57 of the motion magnifying arm 53 is spaced a considerabledistance from the axis of the shaft 46, the spacing between said shaftaxis and the end 57 being considerably greater than the spacing betweenthe shaft axis and the points of engagement of the follower portions 52and 54 with their respective slide blocks.

From the foregoing it will be appreciated that a relatively smallvertical movement imparted to either follower will induce a rotation ofthe shaft and cause a concomitantly far larger movement of the end 57 ofthe motion magnifying arm 53.

It will be apparent that, so long as the thickness of the web W passingbetween the rollers 25, 26 remains a constant, the axis of the detectorroller 26 will remain in a predetermined vertical plane; the weights 50normally urging the roller 26 against the surface of the web ridingaround roller 25. However, it will be understood further that in theevent of a thickness variation in the web or the passage of detritusbetween the rollers, the axis of the detector roller 26 will be elevatedor tilted within a vertical plane common to the axes of the rollers 25,26. It is the function of the detecting and control mechanism next to bedescribed to respond to any such lifting movements of the detectorroller 26, and where such movements exceed a predetermined tolerancerange, to change the sense of a switch set to effect a desired controlfunction.

The control function in the illustrated embodiment is performed by alimit switch 58 carried on the indicator subassembly 59. The arm 53carries a pair of collars 60, 60 which function longitudinally to locatetherebetween a pivotal link 61 mounted in head 61'.

A switch operator rod 62 extends upwardly from the upper end of the link61, the rod 62 being mounted for sliding movement within an opening 62'formed in a horizontal element 63 of the detector mechanism 59. A switchoperator rod 64 extending through a bearing 64 is pivotally mounted in ahead 64" carried by the upper end of rod 62.

It will be appreciated that by a vertical adjustment of rod 62 withrespect to heads 61' and 64", precise control may be achieved in respectof the amount of vertical movement of the rod 62 which is required toactivate (or deactivate) the switch 58. Preferably, an indicator light65, alone or coupled with some audible alarm means, is provided toapprise the operator that thickness tolerances within the web have beenexceeded. Obviously, the mechanism for communicating mechanical motionfrom the arm to the switch may be varied without departing from thespirit of the invention.

Normally, the switch 58 is operably connected to the circuit controllingthe drive means (not shown) for web W in such manner that further feedof the web is interrupted immediately after a flaw or defect is sensed.As a result of this arrangement the flaw within the web will always belocated slightly downstream of the mating area of the rollers 25, 26.Accordingly; the operator will be able to search the web in such areaand, in the event that the defect is manually removable, attend thereto.In the event of serious defects, it may be necessary to cut out theoffending portions of the web and rethread trailing web portions.

The apparatus preferably includes an indicator assembly 66 whichprovides continuous and highly accurate monitoring of the thickness ofmaterial extending between the rollers 25 26. The indicator apparatusincludes a scale 67 having a pointer 68 which is pivoted at 69 at apivot point which is adjacent one end 70 of the pointer.

The link element 71 is pivotally connected at its lower end 72 to theend 57 of the motion magnifying arm 53, the upper end 73 of the linkbeing connected adjacent the end 70 of the pointer 68.

It will thus be appreciated that the indicator assembly 66 provides afurther motion magnification such that even slight vertical movements ofthe motion magnifying arm 53 which may be insufficient to trip theswitch 58 will nonetheless be sufficient to induce considerablemovements of the end 74 of the pointer 68.

The web, after passing through the rollers 25, 26 preferably extendsover a horizontally disposed idler roller 75, under a dancer roller 76,and over a second trailing idler 77. The dancer roller 76, in the usualmanner, is permitted a range of vertical movement while maintaining aconstant tension on the web.

A lower limit switch element 78 may be disposed in the path of theroller 76 at a lower limiting position thereof. Optionally, the switch78 may be employed to interrupt the flow of motive power to the webdrive (not shown) for a predetermined period of time since tripping ofthe switch 78 indicates an excess of the web material.

The web emerging from the roller 77 is passed to the fan fold assembly11 and thence to the remainder of the packaging or other processingapparatus which, in the normal course, functions to sever discretelengths of the web emerging from the fan folder, stuff and discretelengths into suitable envelopes or the like, and thereafter seal theenvelopes. Prior to sealing the envelopes, a reagent may be added to theenvelopes.

The severing, filling, saturating and sealing steps are beyond thepurview of the present application and are mentioned by way ofillustration only.

From the foregoing it will be appreciated that there is provided inaccordance with the present invention, a combined detector and indicatorapparatus which is effective to sense thicknesses in excess of areference thickness and visually to display such thickness variation onan indicator dial or interrupt a circuit, or both.

The thickness variation will be sensed without regard to its widthwiseposition on the web by reason of the unique interconnecting linkagebetween the sensing roller and the controlindicator apparatus.

Referring particularly to FIGS. 3 and 4, for instance, should a defectoccur toward the left-hand side of the web, a clockwise tilting of thedetector roller 26 will result in transmission of a rotary force to theshaft 46 through the follower 52.

Should the defect be nearer to the right hand side of the web, a similarrotation of the shaft 46 will result, the rotation in this instancebeing effected in response to the connection between the shaft 26 andblock 31.

In the event of a centrally located defect, bodily upward movement(unaccompanied by substantial tilting) will also cause a rotation of theshaft 46, effected as a result of the combined action of both of thefollower portions 52 and 54.

While the illustrated embodiment of the apparatus is provided with bothswitching and constant dimension monitoring functions, it will beobvious from the foregoing disclosure that an apparatus displaying onlyone of the noted functions is within the spirit of the presentinvention.

The apparatus is simple, foolproof, and readily adapted for processingof webs of a wide variety of thicknesses and widths.

Having thus described my invention, what I claim as new and desire toreceive by Letters Patent of the United States is:

l. A sensing and control device for detecting thickness irregularitiesand the like at any position across the width of a web of substantialtransverse dimension, comprising: a frame, a reference roller mounted tosaid frame for rotation about a fixed horizontal reference axis, amotion detector roller havin an axis spaced vertically above saidreference roller, a pair 0 mounting means slldably guided in said framefor independent vertical shafting movement, said mounting meansincluding generally horizontally disposed seat portions, bearing meanson each of said mounting means for rotatably supporting the oppositeends of said detector roller, with the axes of said rollers in parallelrelation, web feed means for advancing said web between said rollerswith adjacent peripheral portions of said rollers tangentially engagingopposite faces of said web, a cross-shaft mounted on said frame forpivotal movement about a horizontal axis, a pair of parallel followermeans extending from opposite ends of said shaft, said follower meansbeing supported in respective seat portions of said mounting means, theconnection between said follower means and seat portions causing pivotalmovement of said follower means and said shaft when said mounting meansshifts about a horizontal axis normal to the axis of said cross-shaft,pressure means yieldingly urging said follower means against saidmounting means, motion magnifying means operably connected to said shaftfor movement responsive to pivotal movements of said shaft, and a switchmeans actuated responsive to predetermined movements of said magnifyingmeans.

2. The device in claim 1 and including a spring blade member yieldinglyurged against said detector roller, said blade member engagingsubstantially the entire upper face of said roller, thereby to cleardetritus therefrom.

3. The device in accordance with claim 1 and including indicator meansoperatively connected to said motion magnifying means, said indicatormeans including additional motion magnifier means. I

I i II t

1. A sensing and control device for detecting thickness irregularitiesand the like at any position across the width of a web of substantialtransverse dimension, comprising: a frame, a reference roller mounted tosaid frame for rotation about a fixed horizontal reference axis, amotion detector roller having an axis spaced vertically above saidreference roller, a pair of mounting means slidably guided in said framefor independent vertical shifting movement, said mounting meansincluding generally horizontally disposed seat portions, bearing meanson each of said mounting means for rotatably supporting the oppositeends of said detector roller, with the axes of said rollers in parallelrelation, web feed means for advancing said web between said rollerswith adjacent peripheral portions of said rollers tangentially engagingopposite faces of said web, a cross-shaft mounted on said frame forpivotal movement about a horizontal axis, a pair of parallel followermeans extending from opposite ends of said shaft, said follower meansbeing supported in respective seat portions of said mounting means, theconnection between said follower means and seat portions causing pivotalmovement of said follower means and said shaft when said mounting meansshifts about a horizontal axis normal to the axis of said cross-shaft,pressure means yieldingly urging said follower means against saidmounting means, motion magnifying means operably connected to said shaftfor movement responsive to pivotal movements of said shaft, and a switchmeans actuated responsive to predetermined movements of said magnifyingmeans.
 2. The device in claim 1 and including a spring blade memberyieldingly urged against said detector roller, said blade memberengaging substantially the entire upper face of said roller, thereby toclear detritus therefrom.
 3. The device in accordance with claim 1 andincluding indicator means operatively connected to said motionmagnifying means, said indicator means including additional motionmagnifier means.